International Journal of Scientific and Research Publications, Volume 9, Issue 4, April 2019 183 ISSN 2250-3153 Late Maastrichtian to Paleocene sediments of part of Southwestern Iullemmenden Basin, Rabah Sheet 11, Sokoto State, Northwestern, Nigeria. Sulaiman, Sulaiman Abba1*, Mohammed Rilwan2 1 Department of Geology, Ahmadu Bello University, Zaria 2 Nigerian Institute for Oceanography and Marine Research, Lagos DOI: 10.29322/IJSRP.9.04.2019.p8828 http://dx.doi.org/10.29322/IJSRP.9.04.2019.p8828 Abstract- The stratigraphy and sedimentary structures of the area central region of Niger. The term Iullemmenden Basin was first around Gidan Marafa and environs of Late Maastrichtian to proposed by Raider (1957) to describe the sedimentary basin Paleocene in SW Iullemmeden Basin Nigeria. Detailed field work which extends from Mali to western boundary of the Republic of was carried out on a scale of 1:25,000 and two groups were Niger and Northwestern Nigeria into eastern Niger. The encountered. However, three Formations was studied as follows Iullemmenden Basin is a Cratonic Basin created by tectonic starting from younger to older; (2) Rima Group; only Wurno epiorogenic movement within carbonic rocks (Betrand-Safarti, Formation was found at the top of this group and are made up of 1977). Faure (1966), suggested that the emergence of plate friable, yellow-golden brown fine to medium grained sandstones tectonic theory and seafloor spreading to explain the origin of which intercalates with carboniferous mudstones. This Formation Iullemmeden Basin which was affected by series of marine is separated above with Dukanmaje Formation by bone bed with transgressions during the Paleozoic, Mesozoic and Tertiary age distinct boundary, (1) Sokoto Group; two Formations were respectively. These transgressions progressively affected a great analysed. At the base, Dange Formation was studied; it was portion of the in a southward direction. This implies that the formed during early Paleocene age and are made up of bluish to tertiary marine transgression was the most extensive and covered dark grey shale and thin beds of fibrous gypsum, fine sandstones a considerable portion of the basin. Maastrichtian and Paleocene and intercalating limestone while at the top, Kalambaina marine beds outcrop extensively in the Sokoto region of Formation was studied. It is predominantly made up of thick, Northwestern Nigeria, Central West Africa and continue white limestone bed and at some place it is sandwiched between northeastward in the neighbouring Niger Republic. The deposits overlying and underlying shale bed. Structures observed are consist of siltstones, shales and organogenic marls were laid down parallel lamination and mud cracks. Moreover, fossils observed in and around the Saharan Epeiric Sea that flooded the central are echinoids, ostracods and bivalves. However, based on the Sahara during Latest Cretaceous and Early Tertiary times. An sedimentological analysed results, change in energy regime and embayment of the Saharan sea extended into Sokoto in fossils present, the environment suggest to be of shallow marine. northwestern Nigeria (Kogbe and Lemoigne 1976; Petters, 1978). The geological map of the Sokoto Basin of northwestern Nigeria Index Terms- Stratigraphy, Sedimentary structures, Gidan (Fig. 1). Marafa, Late Maastrichtian, Paleocene, Iullemmeden Basin, Wurno Formation Dange Formation, Kalambaina Formation, limestone, shale, gypsum, bioturbation, echinoids, bivalves, II. GEOLOGIC SETTING AND SEDIMENT depositional cycle, Marine environment, coastal plain DEPOSITION sedimentation The Iullemmenden Basin seems to have started to subside in Permo-Triassic era and to have experienced gradual down warping during the Upper Cretaceous – Lower Tertiary eras, while I. INTRODUCTION steadily filling with sediments. Two prominent fault trends run he Iullemmenden Basin is a major Sub-Sahara Inland Basin NNE-SSW through the centre of the basin while, WSW-ENE T in West Africa extending about 1000 km north to south and faults trends are found in the northeast of the basin near the Air 800 km east to west. It covers western part of Niger, some portion Mountains. The sediments from Cambrian to Pleistocene eras are of Algeria, Mali, Benin and Nigeria. It is named after the 1,500 to 2,000 meters deep, with alternating layers formed when Iullemmenden, a federation of Tuareg people who live in the then basin was undersea and above sea level. http://dx.doi.org/10.29322/IJSRP.9.04.2019.p8828 www.ijsrp.org International Journal of Scientific and Research Publications, Volume 9, Issue 4, April 2019 184 ISSN 2250-3153 Figure 1: Geological sketch map of the southeastern sector of the lullemmeden Basin (Sokoto Basin) (After Kogbe, 1981). The Basin extends over 700,000 km2 and is bounded to the about 100 m of shale sandstone and black fossiliferous limestone. north by Adrar des iforas the Hoggar and Air range/mountain to The beds are folded and represent the earliest documented the west by Gourma, the liptako and crystalline rocks of the evidence of the first marine transgression in Iullemmenden basin northern boundary of Benin Republic and the Nigeria basement during the Cretaceous. At that time, the Iullemmenden basin was rocks to the south and southeast. The basement is directly overlain marked by a series of sedimentary cycles resulting from the by Cambrian beds to the north in the Tesseli and the Hoggar uplifting of the north eastern margin of the Basin (Greigret, 1966) Mountain. As one traverse the basin from the north towards the recognized three transgressions in the Iullemmeden basin during southwest the formations become younger in age and rest directly the cretaceous transgression characterized by the abundance of the on Precambrian basement. This phenomenon is overlap where laower turonian ammonite and the one characterized by the progressively younger beds rest older series. According to Kogbe, abundance of upper Maastrichtian ammonite Libycoceras. Each of (1979) the Iullemmenden Basin was affected by a series of marine the transgression overlap the proceeding one in the upliftment of transgressions during the Paleaozoic Mesozoic and Tertiary. The Air Mountain closed the North-Eastern passage of the sea east of Cenomanian is marine throughout most of the Iullemmenden the Hoggar. Basin. It is characterized by the presence of neolobites a well- known Upper Cenomanian Ammonite. The Cenomanian overlies Geologic Deposition Sequence of Northwestern Sedimentary the Tegama Group of sediments uncomfortably and consist of Basin Table 1: Summary of geological sequence in the northwestern Nigeria sedimentary Basin (Kogbe, 1979). AGE FORMATION GROUP ENVIRONMENT Quaternary Sandy drift, laterites - Continental Eocene to Gwandu Formation Continental Terminals Continental Miocene Gamba Formation Paleocene Kalambaina Formation Sokoto Group Marine Dange Formation http://dx.doi.org/10.29322/IJSRP.9.04.2019.p8828 www.ijsrp.org International Journal of Scientific and Research Publications, Volume 9, Issue 4, April 2019 185 ISSN 2250-3153 Wurno Formation Brackish water with Maastrichtian Dukanmaje Formation Rima Group brief intercalation Taloka Formation Lowermost Illo Formation Continental Intercalaire Continental Cretaceous or Gundumi Formation Older PRECAMBRIAN BASEMENT COMPLEX selected from different locations for sieve analysis. Samples were III. METHODOLOGY carefully disaggregated with the help of pestle and mortar. The This study was undertaken in four stages; weight of the bottom pan, selected empty sieves (2.00 mm, 1.00 i. Desk study, which involved a detailed review of mm, 0.5 mm, 0.25 mm, 0.125 mm and 0.063 mm) and 100 g of published and unpublished literature, each disaggregated samples were obtained using a weighing ii. Fieldwork and sample collection, balance. The sieves and the bottom pan were fastened to a iii. Laboratory analysis, mechanical shaker, and the 100 g of the sample poured on the iv. Processing of data and Compilation upper sieve. The machine was switched on and allowed to shake Desk Study for ten (10) minutes. Sediment in each of the sieves and the bottom This involved detailed reviewed into the previous work pan were weighed and recorded. During the course of the sieve carried out in and around the study area, specifically on Wurno, analysis care was taken in the separation of the sieves after shaking Kalambaina and Dange Formation respectively by past workers. to avoid spillover of the retained sediments. When disaggregating Relevant materials including topographic base map, journals, the samples care was also taken to avoid crushing and grinding in textbooks, maps, published and unpublished works were order not to distort the original shape of the grains. The cumulative consulted. frequency curves resulting from the analyses are shown in Table 2. The results obtained from the sieve analysis are presented in a Fieldwork tabular form (see Table 3). However, the cumulative frequency The study area form parts of Rabah Sheets 11. It cover a curves, critical percentiles (Φ5, Φ16, Φ25, Φ50, Φ75, Φ84 and total area of 13.27 km2. ). It falls within latitude 13o 27ʹ 18ʹ N – Φ95) obtained was used for the calculation of grain size 13o 00ʹ N and longitude 5o 30ʹ E – 5o 34ʹ 25ʹ. The fieldwork was parameters such as; graphic mean, sorting (graphic standard conducted during the dry season on 1: 25,000 scale topographic deviation), graphic skewness and graphic kurtosis; the results of base maps, in order to establish sections and determine the parameters for each of the